This invention relates generally to spray-arms, and, more particularly, to spray-arm assemblies for dishwashers.
One type of domestic dishwasher includes a lower spray-arm mounted in a lower region of a wash chamber, and a mid-level spray-arm mounted above the lower spray-arm. See, for example, U.S. Pat. No. 3,969,137. Typically, the lower spray-arm sprays water upward over dishware and items to be cleaned in a lower rack, and the mid-level spray-arm sprays water upward over dishware and items to be cleaned in an upper rack. A pump injects water into the lower spray-arm for rotary motion thereof, and further directs a stream of water through the lower spray-arm for xcex8 receipt by the mid-level spray-arm and for imparting rotary motion to the mid-level spray-arm. The mid-level spray-arm is mounted to the upper rack, and a sealed retractable tower coupled to the lower spray-arm delivers water from the lower spray-arm to the mid-level spray-arm when water pressure reaches pre-determined levels. The mid-level spray-arm rotates or spins relative to the upper rack upon a bearing surface.
The bearing surface of the mid-level spray-arm, however, tends to wear unevenly. Uneven wear of the bearing surface can lead to impaired performance of the spray-arm and premature jamming and failure of the bearing surface which may prevent the mid-level spray-arm from rotating. In addition, sealing the connection of the retractable tower to the upper and lower racks adds to the cost and complexity of the spray-arms, and consequently increases manufacturing and assembly costs. Still further, known mid-level spray-arms tend to generate considerable noise from spray-arm water jets that impact side walls of the washing chamber.
Accordingly, it would be desirable to provide a mid-level spray-arm assembly that promotes more even wear of the bearing surface, thereby extending the bearing life of the spray-arm. It would also be desirable to provide a mid-level spray-arm bearing that reduces instances of jamming. Further, it would be desirable to eliminate sealed spray-arm connections to reduce manufacturing costs of dishwashers. Also, it would be desirable to provide a quieter operating spray-arm.
In an exemplary embodiment of the invention, a dishwasher mid-level spray-arm assembly includes a spray-arm, a bracket for supporting the spray-arm on an upper rack of the dishwasher, and a bearing for coupling the bracket and spray-arm and that forms a first bearing surface for rotation of the bearing coupling relative to the bracket and a second bearing surface for rotation of the spray-arm relative to the bearing coupling. The first and second bearing surfaces promote a more even wear of the bearing surface, and further allow rotation of the spray-arm even when one of the bearing surfaces fails or jams.
More specifically, the spray-arm includes a hub having an outer surface and a hub slot. The bracket includes an inner surface and a bracket slot, and the bearing coupling is retained partially in the hub slot and partially in the bearing slot. The coupling is an annular disk clip partially retained in the hub slot and partially retained in the bracket slot. A small gap separates the bracket inner surface from the hub outer surface to substantially eliminate frictional engagement of the bracket inner surface and the hub outer surface, and relative rotational movement of the bearing coupling and bracket, and also relative rotation of the spray-arm hub and the bearing coupling is accomplished on smooth first and second bearing surfaces.
The spray-arm hub includes a funnel that accommodates an off-centering or misalignment of the spray-arm with respect to a retractable tower that supplies water to the mid-level spray-arm, and also includes angled fluid discharge ports arranged so that spray-arm water jets do not impact side walls of a dishwasher wash chamber during washing operation. Specifically, a spray pattern of the mid-level spray-arm is substantially confined within a lower outer perimeter of the upper rack of the dishwasher, and items placed at the lower outer perimeter intercept the outer perimeter of the spray pattern and prevent water from impacting the side walls of the wash chamber. Noise from excitation of the wash chamber side walls is considerably reduced and a noticeably quieter operating dishwasher is realized.
The spray-arm assembly is easily assembled with snap-fit engagement of the bearing coupling to the bracket, and snap-fit engagement of the bracket and coupling to the spray-arm hub. Thus, a long life, easily assembled spray-arm assembly is provided.